1. Field of the Invention
The present invention relates to semiconductor devices and methods of manufacturing the semiconductor devices. In particular, the present invention relates to semiconductor devices including memory elements and methods of manufacturing the semiconductor devices including memory elements.
2. Description of the Related Art
In recent years, semiconductor devices have been improved significantly. As integration and density of semiconductor devices become higher, miniaturization of various element patterns therein such as transistors or capacitors has been rapidly progressed. There are strong demands for semiconductor devices which are small in size and large in capacity and can be manufactured at low cost. To fulfill such demands, it is essential to further miniaturize various element patterns. As well as reduction in size of transistors, memory elements, capacitors, and the like for reducing an area occupied by such elements, manufacture of such elements at low cost are necessary. Development of structures of such elements has been actively conducted to meet the need.
For example, in Patent Document 1 (Japanese Published Patent Application No. 2000-269512), in a pixel matrix circuit including thin film transistors, a capacitor (a transistor-type capacitor) has one electrode of a semiconductor film which is doped with an impurity element, the other electrode of a conductive film which corresponds to a gate electrode of a transistor, and an insulating film between the two electrodes which corresponds to a gate insulating film of the transistor, so that capacitance per unit area is increased. Therefore, an area occupied by elements is reduced in the device of Patent Document 1.